I think as it stands only TVPaint Professional 64-bit would run on Mojave. So upgrading to TVP 11 Standard would probably not help but upgrading to the Pro versions of TVP 11 or TVP 10.5 (if that is an option) might.

Standard is 32-bit and I believe that Apple no longer supports 32-bit apps as of Mojave

In fact, 32-bits apps are still working on Mojave but should stop on the next MacOS (10.15) which will come next year.
I did some test and the standard version of TVPaint 11.0.8 in 32bits is working on Mojave. Moreover, to prevent any problem in future, we are working on a 64-bits standard version of TVPaint 11 which should be released soon (Unfortunally I can't tell when).

few days ago,
I've upgraded to mojave genuine version by classic macpro 5.1
but, couldn't run TVP 10.5 on it after installed.

We will do some test with the 10.5 version and we will come back to you as soon as possible.

Standard is 32-bit and I believe that Apple no longer supports 32-bit apps as of Mojave

In fact, 32-bits apps are still working on Mojave but should stop on the next MacOS (10.15) which will come next year.
I did some test and the standard version of TVPaint 11.0.8 in 32bits is working on Mojave. Moreover, to prevent any problem in future, we are working on a 64-bits standard version of TVPaint 11 which should be released soon (Unfortunally I can't tell when).

As JeremyN has said, Mojave still supports 32-bit so your issue is probably something else. Still, you may want to double check if you are using the 32-bit or 64-bit version of TVPaint Pro. I have found that many issues that exist with 32-bit on OSX are resolved by using 64-bit. If you are already using 64-bit - I have no further suggestions

You wrote that you can't launch TVPaint so it might be an issue related to Sentinel driver. Unfortunally, even if we know how to fix this issue, it will be useless on Mojave with TVPaint 10.5.
I manage to successfully launch TVPaint 10.5 on Mojave but the application window remains... grey. Buttons, text, drawing area... are invisible (or are not drawn on the screen), you can't do anything inside in the software.
Maybe this is the issue you are facing ?

I'm am sorry to said this but we don't provide debug support for TVPaint 10.5 anymore , because the source code is too old and cannot be maintened, many changes happened in Apple framework since the release of TVPaint 10.

I really don't like the idea of forcing you to update and buy TVPaint 11 , but this is the only way if you want to use TVPaint on Mojave. I can only tell you that TVPaint 11 works on Mojave in 32bits and 64bits... but you can have some issues installing it correctly so, if you want to buy TVPaint 11, follow what is written on this topic to install it: viewtopic.php?f=10&t=10944#p103514 (it's for MacOS High Sierra but it's the same for Mojave).

The main difference between 32bits and 64bits is the available memory. On 32bits, TVPaint can be slow with very big project (like 4K).

To come back to your issue (the grey interface on 64bits), just before my previous post, we discover the problem appears also in TVPaint 11.0.0, 11.0.1 and 11.0.2 in 64bits but not in 32bits. (that's why I ask you to test with a 32bits)
It's because, I think, the part of the code which draw the interface on the screen is bad on this version... and we change it for 11.0.3. The current version of TVPaint is 11.0.8 so there is no problem with this one on 64bits.

TVPaint 10 32bits works on Mojave because it uses a very old system to draw the interface on the screen, which is completely different from the one used in 64bits.
Unfortunaly, we can't fix this issue on TVPaint 10 64bits, the source code is too old.

Anyway, you can still use TVPaint 10 32bits on Mojave or you can upgrade to TVPaint 11. It's up to you .